1. Field of the Invention
The present invention relates to the technical field of touch panels and, more particularly, to a driving method for reducing display interference in in-cell multi-touch panel and a system using the same.
2. Description of Related Art
The principle of touch panels is based on different sensing manners to detect a voltage, current, acoustic wave, or infrared to thereby detect the coordinates of touch points on a screen where a finger or other medium touches. For example, a resistive touch panel uses a voltage difference between the upper and lower electrodes to compute the position of a pressed point for detecting the location of the touch point, and a capacitive touch panel uses a capacitance change generated in an electrostatic combination of the arranged transparent electrodes and a human body to generate a current or voltage for detecting touching coordinates.
A typical flat touch display is produced by stacking a touch panel directly over a flat display. Since the stacked touch panel is transparent, the image on the flat display can be displayed by passing through the stacked touch panel, and the touch panel can act as an input medium or interface. However, such a stacking requires an increased weight of the touch panel, resulting in relatively increasing the weight of the flat display, which cannot meet with the compactness requirement for current markets. Thus, when the touch panel and flat display are stacked directly, the increased thickness reduces the transmittance of rays and increases the reflectivity and haziness, resulting in relatively reducing the display quality on the screen.
To overcome this, the embedded touch control technology is adopted. The currently developed embedded touch control technologies are essentially on-cell and in-cell technologies. The on-cell technology uses a projected capacitive touch technology to form sensors on the backside (i.e., a surface for attaching a polarized plate) of a color filter (CF) for being integrated into a color filter structure. The in-cell technology embeds a sensor in LCD cells to thereby integrate a touch element with a display panel such that the display panel itself is provided with a touch function without having to be attached or assembled to a touch panel. The in-cell multi-touch panel technology is getting more and more mature, and since the touch function is directly integrated during a panel production process, without adding a layer of touch glass, the original thickness is maintained and the cost is reduced.
FIG. 1 is a schematic diagram of a typical in-cell multi-touch panel system. As shown in FIG. 1, the panel system is comprised of a display controller 110 and an in-cell multi-touch panel 130. The display controller 110 includes a touch controller 111 and a display driver 113.
The display driver 113 outputs red (R), green (G), and blue (B) pixel signal to the in-cell multi-touch panel 130 for displaying an image. In addition, the touch controller 111 outputs a touch driving signal to the in-cell multi-touch panel 130 through a control signal or a common signal Vcom[1:N]. The in-cell multi-touch panel 130 thus receives a sensing signal Sensing[1:M] for performing a touch detection.
FIGS. 2(A)-2(C) are schematic diagrams of a common voltage layer (Vcom) and a touch driving layer in a typical in-cell multi-touch panel 130. As shown in FIG. 2(A), the touch driving layer (Tx) is arranged at the same layer as the common voltage (corn) layer on displaying. As shown in FIG. 2(B), the touch driving layer (Tx) is arranged separately from the common voltage (corn) layer on displaying, and in this case there is a sensing electrode layer (Rx) disposed between the touch driving layer (Tx) and the common voltage (com) layer. As shown in FIG. 2(C), the touch driving layer (Tx) is arranged separately from the common voltage (com) layer on displaying, and in this case there is a sensing electrode layer Rx disposed above the touch driving layer (Tx).
The touch driving layer (Tx) and the common voltage (com) layer on displaying are designed in FIG. 2(A) to share the same layer of transparent electrical conductor. Such a configuration requires a time sharing scheme in displaying and in touch sensing for using the conductor lines of the common voltage (corn) layer, so as to avoid noise interference and affecting the display quality on touch sensing. However, for maintaining a frame rate at 60 Hz and concurrently using the conductor lines of the common voltage (com) layer on displaying and on touch sensing, the time shared by the displaying and the touch sensing is limited. The prior art applies a special driving timing to concurrently drive displaying and touch sensing. This is done by separating the gate working interval of a display from the touch driving operating interval of a touch sensing, so as to prevent the displaying and the touch sensing from using the conductor lines in the common voltage (com) layer of the same block. As shown in FIGS. 2(B) and 2(C), the touch driving layer (Tx) and the common voltage (com) layer in the in-cell multi-touch panel can be arranged not to share the same conductor layer. Ideally, the cited panel structures and driving methods, as shown in FIGS. 2(A)-2(C), can achieve concurrent displaying and touch sensing without mutual interference for thus normally displaying a frame. However, in practice, the panel structures and driving methods in FIGS. 2(A)-2(C) may cause a coupling effect due to the operation of a touch driving signal on touch sensing, resulting in that the display frame is irregularly disturbed.
Therefore, it is desirable to provide an improved driving method and system to mitigate and/or obviate the aforementioned problems.